In the field of modern drilling, efficiency and precision are crucial, especially in challenging terrains with fractured rock or loose formations. This is where Casing Advance Systems (CAS) play a transformative role. These advanced systems allow for both drilling and casing placement simultaneously, enhancing hole stability, speed, and safety in various drilling applications.
The majority of the earth is covered with loose, unconsolidated material and Casing Advance Systems are specialized drilling technologies designed to support drilling in these difficult environments by advancing the casing as the hole is drilled. This method is particularly useful in terrains where loose, unstable ground can hinder progress, providing a controlled pathway that reduces risks and enhances drilling precision.
CAS operates by creating a larger hole than the outer advancing casing tube. As this continuous drilling progresses it stabilizes the borehole walls and prevents material from collapsing back into the drilled area This makes it possible to drill down into solid bedrock passing through material such as sands, clays and boulders, while maintaining structural integrity.
One of the most significant benefits of CAS is the speed at which it enables projects to move forward. By stabilizing the borehole during drilling, CAS reduces the time spent dealing with borehole collapse or loose debris when open hole drilling, making it possible to reach greater depths faster.
CAS technology can lead to substantial cost savings, particularly for projects where reusable casing is only needed during the drilling process to keep the drilled hole open and not forming part of the finished structure. Temporary casing is a an economical solution for drilled anchors / tie backs or construction piles as the outer casing is reclaimed and reused.These systems minimize material waste, reduce equipment wear, and lower overall project costs.
In environments with fractured or unstable rock, CAS offers enhanced drilling precision by minimizing borehole deviation. By design these full face drilling systems help keep the casing stable & aligned ensuring the CAS completes the bore hole accurately.
DKI’s wing type drilling system is ideal for casing holes through loose overburden, down and into solid bedrock. This simple design with ground engineering applications in mind is easily paired with DKI’s range of DTH hammers. Replaceable wings and other key components, with sizes starting at casing outer diameter 4.5” (115 mm) through to the 36” (914 mm)
The DKI Concentric-Type Casing Advance System features a simple, yet robust and proven, design comprised of a Pilot Bit, a Casing Shoe and a Heavy Duty Ring Bit. The pilot bit securely locks into the ring bit via locking lug mechanism to form the robust oversized-looking face similar to a conventional hammer bit. The unique locking mechanism also allows for direct transfer of energy from the hammer to the drilling surface of the ring bit and the pilot bit, which in turn ensures a superior penetration rate. The casing pipe is easily welded to the casing shoe, which threads into the ring bit to sit unrestricted on its shoulder, thus, preventing the casing pipe from rotating during the drilling operation and securing it at the same time.
Casing Advance Systems are frequently used in water well drilling in both urban and built areas where project speed is essential to reduce environmental impact. These systems are ideal for casing off the loose ground and overburden to form part of the water well
With the ever increasing geothermal heating of domestic houses and increasingly nowadays the commercial sector due to the potential cost savings and environmental concerns, casing advancement systems have never been more relevant when drilling holes through the overburden. These systems make it much easier to reach the necessary hole depths with minimum disruption to sub structures and any existing foundations.
It's common practice these days for CAS to be used for both friction and end bearing piles. The casings can be used to form part of the foundation structure or as a temporary solution and be retrieved. Either way ensures structural safety and integrity during the building process.
Site investigations are a key part of accessing suitability for any structural development. CAS are a useful and precise tool to reach any necessary drilled hole depths to allow for an overburden sample to be taken usually by coring method.
